Symmetricom Time Server - Manual (Page 106)

A-92 TimeVault™ User’s Manual 6000-100AppA.fm Rev. C
Appendix A: NTP Version 3, NTPQ, and NTPDC NTP V 3.0 Data Format per RFC-1305
Figure A-1 NTP Data Packet Information Layout
Leap Indicator
The leap indicator is a 2 bit code that signals an impending leap second to be added or
subtracted in the last minute of the current day. Leap year codes and their corresponding
meanings are shown in Table A-1 below:
Table A-1 Leap Year Codes
The unsynchronized state is indicated by TimeVault whenever the estimated
synchronization error is greater than the root dispersion. Such conditions typically occur
following turn-on, until synchronization with the external source has been achieved, and
whenever the external synchronization input has been removed and the extrapolated time
error has exceeded the value of the root dispersion.
Version Number
The version number is a three bit integer that specifies the NTP version. TimeVault will
copy this field from the client requesting packet and return it in this field if it is equal to
either 2 or 3. NTP version 1 packets are not supported.
Mode
The mode is a three bit integer that determines the functions TimeVault performs.
TimeVault operates in mode four or server mode. Mode four operation allows the module
to synchronize hosts but will not allow the module to be synchronized by another host.
Leap Indicator Version Number Mode Stratum Poll Precision
Synchronizing Distance (Root Delay Version 3)
Synchronizing Dispersion (Root Dispersion Version 3)
Reference Clock Identifier
Reference Timestamp
Originate Timestamp
Receive Timestamp
Transmit Timestamp
Authenticator
Bit 0 Bit 1 Meaning
0 0 Normal Operation
0 1 61 second last minute
1 0 59 second last minute
1 1 Clock not synchronized